Corrosion protection of mild steel by organic inhibitors

Abstract

Mild steel is a very important industrial metal and it uses in several operational units. Bulk amount of sulphuric acid is used with phosphate raw materials during production phosphate fertilizer. Mild steel is a sensitive metal in acidic medium. It starts corrosion reaction with metal. It changes their physical, chemical and mechanical properties, tarnishes their facial appearance and its deterioration occurs due to corrosion reaction. Metal is suffering from various types of corrosion like galvanic corrosion, pitting corrosion, crevice corrosion, stress corrosion and other types of corrosion. Organic inhibitors 2-(aminomethyl) phenol and 2-(aminomethyl) aniline are used as corrosion resistance for this work. These inhibitors anticorrosive properties studied at different temperatures 600C, 700C and 800C and 5mM their concentration. The corrosion rate of metal was calculated by gravimetric technique. Corrosion current density was determined potentiostatic polarization techniques. Inhibitors' surface adsorption phenomenon, thermal stability, physisorption-chemisorption activities, surface films formation were studied by application of activation energy, heat of adsorption, free energy, enthalpy and entropy. Inhibitors occupied space on interface i.e. confirmed by surface coverage area and inhibition efficiency. Potentiostat results were shown that these inhibitors developed polarization on the surface of base metal.